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20 Cards in this Set
- Front
- Back
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What is the embryological origin of:
1) anterior pituitary 2) posterior pituitary |
1) Rathke's pouch - invagination of pharyngeal epithelium (epithelioid type cells)
2) Neural tissue outgrowth from the hypothalamus (glial type cells) |
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Hormones of the anterior pituitary
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1. Growth hormone (GH, somatotropin)
2. Thyroid stimulating hormone (TSH, thyrotropin) 3. Adrenocorticotrpin (ACTH, corticotropin) 4. Prolactin (PRL) 5. Follicle stimulating hormone (FSH) 6. Luteinzing hormone (LH) |
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Hormones of the posterior pituitary
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1. Vasopressin (ADH, anti-diuretic hormone)
2. Oxytocin |
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Hormones from somatotropes perform what functions?
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GH - sitmulate lipolysis, body growth, secretion of IGF-1; inhibits actions of insulin on carbohydrates and lipid metabolism
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What does the hormone secreted by corticotropes do?
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ACTH- stimulates production of glucocorticoids and androgens by the adrenal cortex; maintains site of zona fasciculata and zona reticularis of cortex
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TSH is secreted by what type of cells? What does TSH do?
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Secreted by thyrotropes. Stimulates production of thyroid hormones by thyroid follicular cells and maintains the size of the follicular cells
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Gonadotropes release two hormones - name them and explain their functions
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1. FSH - growth of follicles in the ovaries and sperm maturation in the Sertoli cells of testes
2. LH - stimulates testosterone synthesis in Leydig cells of testes; stimulates ovulation, formation of corpus luteum, and estrogen and progesterone synthesis in ovaries |
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Lactotropes and mammotropes secrete what? What is the function of the secreted hormone?
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Prolactin - stimulates milk secretion and production
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What are the most abundant cells in the anterior pituitary?
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Somatotropes (30-40%)
Corticotropes (20%) (all others ~5% each) |
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Which anterior pituitary cells are acidophilic? Basophilic?
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Acidophilic - somatotropes, lactotropes
Basophilic - Corticotropes, Thyrotropes, gonadotropes |
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What is the function of ADH?
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Controls rate of water excretion into the urine, thereby controlling concentration of water in body fluids
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Function of oxytocin?
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Helps to express/eject milk from glands of breast and helps in uterine contractions during delivery
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Where are the bodies of the cells that secrete posterior pituitary hormones?
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Located in the magnocellular divisions of supraoptic (ADH) and paraventricular (oxytocin) nuclei of the hypothalamus. They are then transported in axoplasm of neuron nerve fibers going to the pituitary gland
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Will pituitary secretions be altered if proximity to hypothalamus changed?
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Yes, neuronal connections are responsible for pituitary secretion (signals start from hypothalamus)
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What directly influences the anterior pituitary secretions?
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Hypothalamic relasing or inhibitory factors
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Describe blood flow to the anterior pituitary.
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Blood flow from lower hypothalamus capillary plexus travels through hypothalamic-hypophysial portal blood vessels into the anterior pituitary sinuses. Arteries penetrate the medicine eminence, and then additional ones leave the eminence, with the connections forming the portal system.
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Hypothalamic releasing and inhibiting hormones are carried from the hypothalamus to ...?
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Median eminence and tuber cinereum, and are then absorbed into the hypothalamic-hypophysial portal system
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Hypothalamic hormones
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1. Thryotropin-releasing hormone (TRH) - release of TSH
2. Corticotropin-releasing hormone (CRH) - release of adrenocorticotropin 3. Growth hormone releasing hormone (GHRH) - release of GH 4. Growth hormone inhibiting hormone (GHIH, somatostatin) - inhibit GH secretion 5. Gonadotropin releasing hormone (GnRH) - release of FSH and LH 6. Prolactin inhibitory hormone (PIH) - inhibition of prolactin secretion |
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Structure of prolactin-inhibiting hormone (PIH)
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Dopamine (catecholamine)
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Electrical stimulation of the median eminence can cause?
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Release of hypothalamic hormones because neurons secrete these factors into the median eminence before transport to the anterior pituitary
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